feat(api-logs): Add delegating no-op logger provider

experimental/CHANGELOG.md

@@ -9,6 +9,8 @@ All notable changes to experimental packages in this project will be documented
 
 ### :rocket: (Enhancement)
 
+* feat(api-logs): Add delegating no-op logger provider [#4861](https://github.com/open-telemetry/opentelemetry-js/pull/4861) @hectorhdzg
+
 ### :bug: (Bug Fix)
 
 * fix(sampler-jaeger-remote): fixes an issue where package could emit unhandled promise rejections @Just-Sieb

experimental/packages/api-logs/src/ProxyLogger.ts

@@ -0,0 +1,69 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { NOOP_LOGGER } from './NoopLogger';
+import { Logger } from './types/Logger';
+import { LoggerOptions } from './types/LoggerOptions';
+import { LogRecord } from './types/LogRecord';
+
+export class ProxyLogger implements Logger {
+  // When a real implementation is provided, this will be it
+  private _delegate?: Logger;
+
+  constructor(
+    private _provider: LoggerDelegator,
+    public readonly name: string,
+    public readonly version?: string | undefined,
+    public readonly options?: LoggerOptions | undefined
+  ) {}
+
+  /**
+   * Emit a log record. This method should only be used by log appenders.
+   *
+   * @param logRecord
+   */
+  emit(logRecord: LogRecord): void {
+    this._getLogger().emit(logRecord);
+  }
+
+  /**
+   * Try to get a logger from the proxy logger provider.
+   * If the proxy logger provider has no delegate, return a noop logger.
+   */
+  private _getLogger() {
+    if (this._delegate) {
+      return this._delegate;
+    }
+    const logger = this._provider.getDelegateLogger(
+      this.name,
+      this.version,
+      this.options
+    );
+    if (!logger) {
+      return NOOP_LOGGER;
+    }
+    this._delegate = logger;
+    return this._delegate;
+  }
+}
+
+export interface LoggerDelegator {
+  getDelegateLogger(
+    name: string,
+    version?: string,
+    options?: LoggerOptions
+  ): Logger | undefined;
+}

experimental/packages/api-logs/src/ProxyLoggerProvider.ts

@@ -0,0 +1,55 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { LoggerProvider } from './types/LoggerProvider';
+import { Logger } from './types/Logger';
+import { LoggerOptions } from './types/LoggerOptions';
+import { NOOP_LOGGER_PROVIDER } from './NoopLoggerProvider';
+import { ProxyLogger } from './ProxyLogger';
+
+export class ProxyLoggerProvider implements LoggerProvider {
+  private _delegate?: LoggerProvider;
+
+  getLogger(
+    name: string,
+    version?: string | undefined,
+    options?: LoggerOptions | undefined
+  ): Logger {
+    return (
+      this.getDelegateLogger(name, version, options) ??
+      new ProxyLogger(this, name, version, options)
+    );
+  }
+
+  getDelegate(): LoggerProvider {
+    return this._delegate ?? NOOP_LOGGER_PROVIDER;
+  }
+
+  /**
+   * Set the delegate logger provider
+   */
+  setDelegate(delegate: LoggerProvider) {
+    this._delegate = delegate;
+  }
+
+  getDelegateLogger(
+    name: string,
+    version?: string | undefined,
+    options?: LoggerOptions | undefined
+  ): Logger | undefined {
+    return this._delegate?.getLogger(name, version, options);
+  }
+}

experimental/packages/api-logs/src/api/logs.ts

@@ -24,10 +24,13 @@ import { LoggerProvider } from '../types/LoggerProvider';
 import { NOOP_LOGGER_PROVIDER } from '../NoopLoggerProvider';
 import { Logger } from '../types/Logger';
 import { LoggerOptions } from '../types/LoggerOptions';
+import { ProxyLoggerProvider } from '../ProxyLoggerProvider';
 
 export class LogsAPI {
   private static _instance?: LogsAPI;
 
+  private _proxyLoggerProvider = new ProxyLoggerProvider();
+
   private constructor() {}
 
   public static getInstance(): LogsAPI {
@@ -48,6 +51,7 @@ export class LogsAPI {
       provider,
       NOOP_LOGGER_PROVIDER
     );
+    this._proxyLoggerProvider.setDelegate(provider);
 
     return provider;
   }
@@ -60,7 +64,7 @@ export class LogsAPI {
   public getLoggerProvider(): LoggerProvider {
     return (
       _global[GLOBAL_LOGS_API_KEY]?.(API_BACKWARDS_COMPATIBILITY_VERSION) ??
-      NOOP_LOGGER_PROVIDER
+      this._proxyLoggerProvider
     );
   }
 
@@ -80,5 +84,6 @@ export class LogsAPI {
   /** Remove the global logger provider */
   public disable(): void {
     delete _global[GLOBAL_LOGS_API_KEY];
+    this._proxyLoggerProvider = new ProxyLoggerProvider();
   }
 }

experimental/packages/api-logs/src/index.ts

@@ -26,6 +26,8 @@ export { LoggerOptions } from './types/LoggerOptions';
 export { AnyValue, AnyValueMap } from './types/AnyValue';
 export { NOOP_LOGGER, NoopLogger } from './NoopLogger';
 export { NOOP_LOGGER_PROVIDER, NoopLoggerProvider } from './NoopLoggerProvider';
+export { ProxyLogger } from './ProxyLogger';
+export { ProxyLoggerProvider } from './ProxyLoggerProvider';
 
 import { LogsAPI } from './api/logs';
 export const logs = LogsAPI.getInstance();

experimental/packages/api-logs/test/api/api.test.ts

@@ -15,17 +15,19 @@
  */
 
 import * as assert from 'assert';
-import { Logger, logs } from '../../src';
+import { Logger, ProxyLoggerProvider, logs } from '../../src';
 import { NoopLogger } from '../../src/NoopLogger';
 import { NoopLoggerProvider } from '../../src/NoopLoggerProvider';
 
 describe('API', () => {
   const dummyLogger = new NoopLogger();
 
   it('should expose a logger provider via getLoggerProvider', () => {
-    const provider = logs.getLoggerProvider();
-    assert.ok(provider);
-    assert.strictEqual(typeof provider, 'object');
+    assert.ok(logs.getLoggerProvider() instanceof ProxyLoggerProvider);
+    assert.ok(
+      (logs.getLoggerProvider() as ProxyLoggerProvider).getDelegate() instanceof
+        NoopLoggerProvider
+    );
   });
 
   describe('GlobalLoggerProvider', () => {

experimental/packages/api-logs/test/internal/global.test.ts

@@ -17,6 +17,7 @@
 import * as assert from 'assert';
 import { _global, GLOBAL_LOGS_API_KEY } from '../../src/internal/global-utils';
 import { NoopLoggerProvider } from '../../src/NoopLoggerProvider';
+import { ProxyLoggerProvider } from '../../src';
 
 const api1 = require('../../src') as typeof import('../../src');
 
@@ -66,11 +67,10 @@ describe('Global Utils', () => {
     assert.strictEqual(original, api1.logs.getLoggerProvider());
   });
 
-  it('should return the module NoOp implementation if the version is a mismatch', () => {
-    const original = api1.logs.getLoggerProvider();
-    api1.logs.setGlobalLoggerProvider(new NoopLoggerProvider());
+  it('should return the module no op implementation if the version is a mismatch', () => {
+    api1.logs.setGlobalLoggerProvider(new ProxyLoggerProvider());
     const afterSet = _global[GLOBAL_LOGS_API_KEY]!(-1);
 
-    assert.strictEqual(original, afterSet);
+    assert.ok(afterSet instanceof NoopLoggerProvider);
   });
 });

experimental/packages/api-logs/test/proxy-implementations/proxy-logger.test.ts

@@ -0,0 +1,117 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import * as assert from 'assert';
+import * as sinon from 'sinon';
+import {
+  Logger,
+  LoggerProvider,
+  ProxyLogger,
+  ProxyLoggerProvider,
+} from '../../src';
+import { NoopLogger } from '../../src/NoopLogger';
+
+describe('ProxyLogger', () => {
+  let provider: ProxyLoggerProvider;
+  const sandbox = sinon.createSandbox();
+
+  beforeEach(() => {
+    provider = new ProxyLoggerProvider();
+  });
+
+  afterEach(() => {
+    sandbox.restore();
+  });
+
+  describe('when no delegate is set', () => {
+    it('should return proxy loggers', () => {
+      const logger = provider.getLogger('test');
+      assert.ok(logger instanceof ProxyLogger);
+    });
+  });
+
+  describe('when delegate is set before getLogger', () => {
+    let delegate: LoggerProvider;
+    let getLoggerStub: sinon.SinonStub;
+
+    beforeEach(() => {
+      getLoggerStub = sandbox.stub().returns(new NoopLogger());
+      delegate = {
+        getLogger: getLoggerStub,
+      };
+      provider.setDelegate(delegate);
+    });
+
+    it('should return loggers directly from the delegate', () => {
+      const logger = provider.getLogger('test', 'v0');
+
+      sandbox.assert.calledOnce(getLoggerStub);
+      assert.strictEqual(getLoggerStub.firstCall.returnValue, logger);
+      assert.deepStrictEqual(getLoggerStub.firstCall.args, [
+        'test',
+        'v0',
+        undefined,
+      ]);
+    });
+
+    it('should return loggers directly from the delegate with schema url', () => {
+      const logger = provider.getLogger('test', 'v0', {
+        schemaUrl: 'https://opentelemetry.io/schemas/1.7.0',
+      });
+
+      sandbox.assert.calledOnce(getLoggerStub);
+      assert.strictEqual(getLoggerStub.firstCall.returnValue, logger);
+      assert.deepStrictEqual(getLoggerStub.firstCall.args, [
+        'test',
+        'v0',
+        { schemaUrl: 'https://opentelemetry.io/schemas/1.7.0' },
+      ]);
+    });
+  });
+
+  describe('when delegate is set after getLogger', () => {
+    let logger: Logger;
+    let delegateProvider: LoggerProvider;
+
+    let delegateLogger: Logger;
+    let emitCalled: boolean;
+
+    beforeEach(() => {
+      emitCalled = false;
+      delegateLogger = {
+        emit() {
+          emitCalled = true;
+        },
+      };
+
+      logger = provider.getLogger('test');
+
+      delegateProvider = {
+        getLogger() {
+          return delegateLogger;
+        },
+      };
+      provider.setDelegate(delegateProvider);
+    });
+
+    it('should emit from the delegate logger', () => {
+      logger.emit({
+        body: 'Test',
+      });
+      assert.ok(emitCalled);
+    });
+  });
+});